Touch simulation system and method

ABSTRACT

Systems and methods provide for simulating an effective touch on a touch screen sensor. A touch screen sensor includes a first surface, an opposing second surface, and one or more electrodes disposed on or proximate to the second surface. Signals are applied to the first and second surfaces in a manner which results in a simulated touch to a particular location of the touch screen sensor. In another approach, a plurality of voltage drive signals are applied at various touch surface regions of the touch screen sensor. A current flow resulting from application of the voltage drive signals is detected as the simulated touch. Touch simulation can be initiated locally or remotely as part of automated monitoring, testing, calibration, and/or servicing procedures. Results of a touch simulation procedure can be acquired and used locally or remotely to assess the operational fitness of the touch screen sensor over time.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. Ser. No. 10/346,325, filed Jan.17, 2003, now allowed, the disclosure of which is incorporated byreference in its entirety herein.

FIELD OF THE INVENTION

The present invention relates generally to touch screen sensors and,more particularly, to systems and methods for simulating an effectivehuman touch on a touch screen sensor.

BACKGROUND OF THE INVENTION

A typical touch screen employs a sheet of glass with a conductivecoating, such as indium tin oxide, with four corner terminalconnections. The touch screen may be configured as a capacitive orresistive touch screen, with a pattern of electrodes made of conductivematerial. A finger, stylus, or conductive top sheet can draw or injectcurrent at the point of contact. The current can then distribute to thetouch panel terminals in a proportionate manner relative to the locationof the point of contact.

Touch detection accuracy of the touch screen can change over time due toa number of system and environmental reasons, such as wear duringextended use. Monitoring, testing, and servicing of touch screen systemshas conventionally involved manual evaluation of a suspect system by anon-site technician. Such conventional evaluation and repair approachesare both costly and time inefficient.

SUMMARY OF THE INVENTION

The present invention is directed to systems and methods for simulatingan effective touch on a touch screen sensor. According to oneembodiment, a touch screen sensor includes a first surface, a secondsurface opposing the first surface, and one or more electrodes disposedon or proximate to the second surface. Signals are applied to the firstand second surfaces in a manner which results in a simulated touch to aparticular location of the touch screen sensor. According to anotherembodiment, a plurality of voltage drive signals are applied at aplurality of touch surface regions of the touch screen sensor. A currentflow resulting from application of the voltage drive signals is detectedas the simulated touch.

In accordance with a further embodiment, a touch screen sensor includesa substrate having a first surface and a second surface opposing thefirst surface, and an electrically conductive structure coupled to, orpositioned proximate, the substrate and situated proximate the secondsurface. First and second signals are respectively applied to the firstsurface of the touch screen sensor and the electrically conductivestructure. A touch on the touch screen sensor is simulated by changingone of the first and second signals relative to the other of the firstand second signals. For example, the first and second signals arerespectively applied to the first surface and electrically conductivestructure to develop a potential difference between the first surfaceand the electrically conductive structure. A response to the potentialdifference is detected as the simulated touch.

According to another embodiment, a touch screen sensor includes a firstsurface, a second surface opposing the first surface, and a plurality ofelectrodes disposed on or proximate to the second surface. A firstsignal is applied to the first surface of the touch screen sensor. Oneof a plurality of second signals is applied to each of the plurality ofelectrodes disposed on or proximate to the second surface of the touchscreen sensor. A touch on the touch screen sensor is simulated bychanging a characteristic of at least one of the plurality of secondsignals relative to the first signal.

In accordance with a further embodiment, a touch sensing system includesa touch screen sensor comprising a substrate having a first surface anda second surface opposing the first surface. The system further includesan electrically conductive structure coupled to, or positionedproximate, the substrate and situated proximate the second surface. Acontroller is coupled to the touch screen sensor. The controller isconfigured to apply first and second signals respectively to the firstsurface of the touch screen sensor and the electrically conductivestructure. The controller simulates a touch on the touch screen sensorby changing one of the first and second signals relative to the other ofthe first and second signals.

According to another embodiment, a touch sensing system includes a touchscreen sensor having a first surface, a second surface opposing thefirst surface, and a plurality of electrodes disposed on or proximate tothe second surface. A controller, coupled to the touch screen sensor, isconfigured to apply a first signal to the first surface of the touchscreen sensor and apply one of a plurality of second signals to each ofthe plurality of electrodes disposed on or proximate to the secondsurface of the touch screen sensor. The controller simulates a touch onthe touch screen sensor by changing a characteristic of at least one ofthe plurality of second signals relative to the first signal.

In accordance with yet another embodiment, a touch sensing systemincludes a touch screen sensor comprising a substrate having a firstsurface and a second surface opposing the first surface. A controller,coupled to the touch screen sensor, is configured to apply a pluralityof voltage drive signals at a plurality of regions of the touch screensensor. The controller detects a current flow resulting from applicationof the plurality of voltage drive signals as the simulated touch.

Touch simulation can be initiated locally or remotely as part ofautomated monitoring, testing, calibration, and/or servicing procedures.Results of a touch simulation procedure, such as current and historicaltouch detection accuracy data, can be acquired and used locally orremotely to assess the operational fitness of the touch screen sensorover time.

The above summary of the present invention is not intended to describeeach embodiment or every implementation of the present invention.Advantages and attainments, together with a more complete understandingof the invention, will become apparent and appreciated by referring tothe following detailed description and claims taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a touch screen sensor system which employsa touch simulation capability in accordance with an embodiment of thepresent invention;

FIG. 2 is an illustration of a touch screen sensor system which employsa touch simulation capability in accordance with another embodiment ofthe present invention;

FIG. 3 illustrates a touch screen sensor system which employs a touchsimulation capability, including a remote touch simulation capability,in accordance with a further embodiment of the present invention;

FIG. 4 depicts a touch screen sensor system which employs a touchsimulation capability in accordance with an embodiment of the presentinvention;

FIG. 5 is an illustration of a touch screen sensor configuration whichemploys a single rear electrode in accordance with an embodiment of thepresent invention;

FIG. 6 is an illustration of a touch screen sensor configuration whichemploys a multiplicity of rear electrodes in accordance with anembodiment of the present invention;

FIG. 7 is an illustration of a touch screen sensor configuration whichemploys an electrically conductive structure situated proximate a rearsurface of the touch screen sensor in accordance with an embodiment ofthe present invention;

FIG. 8 is an illustration of a touch screen sensor configuration whichemploys an electrically conductive frame situated proximate a rearsurface of the touch screen sensor and contacting side surfaces of thetouch screen sensor in accordance with an embodiment of the presentinvention;

FIG. 9 is a flow diagram of a methodology for simulating a touch on atouch screen sensor in accordance with an embodiment of the presentinvention;

FIG. 10 is a flow diagram of a methodology for simulating a touch on atouch screen sensor in accordance with another embodiment of the presentinvention;

FIG. 11 is a flow diagram of a methodology for simulating a touch on atouch screen sensor in accordance with a further embodiment of thepresent invention;

FIG. 12 is a flow diagram of a methodology for simulating a touch on atouch screen sensor in accordance with yet another embodiment of thepresent invention;

FIG. 13 is a flow diagram of a methodology for simulating a touch on atouch screen sensor in accordance with an embodiment of the presentinvention;

FIG. 14 is a flow diagram of a methodology for remotely or locallyinitiating simulation of a touch on a touch screen sensor in accordancewith an embodiment of the present invention;

FIG. 15 is a simplified schematic of an near field imaging (NFI)capacitive touch screen sensor configured for automated touch simulationin accordance with an embodiment of the present invention; and

FIG. 16 is a simplified schematic of a grid capacitive touch screensensor configured for automated touch simulation in accordance with anembodiment of the present invention.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It is to be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

In the following description of the illustrated embodiments, referenceis made to the accompanying drawings which form a part hereof, and inwhich is shown by way of illustration, various embodiments in which theinvention may be practiced. It is to be understood that the embodimentsmay be utilized and structural changes may be made without departingfrom the scope of the present invention.

The present invention is directed to systems and methods for simulatinga touch on a touch screen sensor. Simulating a touch on a touch screensensor (TSS) can involve processes effected from, or performed at, aremote site, such as initiating, monitoring, analyzing, or controlling atouch simulation process. Touch simulation methodologies implemented inaccordance with the principles of the present invention provide forenhanced diagnostic, calibration, and maintenance capabilities that canbe used across a number of differing touch screen sensor technologies,including, for example, capacitive, resistive, and hybridcapacitive/resistive TSS technologies.

It has been found that changes in touch detection accuracy can resultduring extended use of a given touch screen sensor. For example, changesin the coordinates detected by a given touch screen sensor can result intouch detection inaccuracies resulting from wear, environmental factors,or characteristics of a particular application or system in which thetouch screen sensor is implemented. It is important that any suchchanges in TSS detection accuracy and overall TSS performance bemonitored so that recalibration or maintenance on the touch screensystems can be initiated when necessary. Traditionally, a skilledtechnician typically gathers such data by performing on-site servicingto the touch screen system, often after TSS performance hassignificantly degraded to a level that adversely impacts use of thesystem.

A touch simulation approach according to the present invention providesfor enhanced monitoring of touch screen sensor performance in a mannerthat can eliminate the need for on-site testing and servicing by askilled technician in many cases. Certain embodiments of the presentinvention provide for local initiation of touch screen sensor diagnosticand calibration tests that involve the simulation of a touch by the TSScontroller or a host computing system which incorporates a touch screensensor. Other embodiments of the present invention provide for remoteinitiation of touch screen sensor diagnostic and calibration tests thatinvolve the simulation of a touch by the TSS controller or a hostcomputing system which incorporates a touch screen sensor.

Touch simulation in accordance with the present invention can beinitiated by software executable by a host computing system whichincorporates a touch screen system or by software/firmware executable bya TSS controller. The touch simulation software can be controllerlocally or remotely via a network connection, for example, preferably atoff-peak times, during periods of TSS idleness, or during regularlyscheduled maintenance. Each time a touch is simulated, the detectedposition of the touch can be recorded locally, such as on the hostcomputing system, and stored in a file or database. Over a period oftime, changes in the value of the recorded touch can be tracked. Trendscan be monitored and, if necessary, maintenance alert messages can beissued. Various operations implicated in TSS monitoring, evaluation, andrepair can be performed locally, remotely, or cooperatively via localand remote resources.

An automated touch simulation approach of the present invention providesfor a highly repeatable touch that can be simulated at a prescribedscreen location with high accuracy. The ability to simulate a touch at aprescribed location with high precision provides for a high resolutionof touch detection accuracy. It can be appreciated that human touchesmade at a prescribed calibration location of a touch screen, forexample, can be subject to significant positional inaccuracies, since arepeated human touch rarely occurs in the same location.

Another source of inaccuracies that can adversely affect conventionalTSS monitoring and testing approaches involves intended or unintendedadjustment to video position, size, and horizontal and verticaldimensions of the display (e.g., cathode ray tube) to which the touchscreen sensor is attached. A touch target on the display will move ifchanges are made to these parameters. When a human uses a predeterminedtouch target of the display to test for touch coordinate movement,repeatability is virtually impossible.

Touch simulation methodologies of the present invention find utility ina wide variety of applications. For example, entertainment systems canbe installed in public locations, such as in arcades, casinos, and bars,where accuracy of touch is essential. At off peak times, or duringsystem startup or shutdown or other predetermined times, a backgroundmaintenance program involving a simulated touch can be run, and anychanges in touch position can be recorded. Changes over time to thetouch position can be monitored, and significant variations can bereported to an operator or owner for servicing. A service engineer can,for example, initiate background maintenance remotely on demand over acomputer network or on site. Such background maintenance routines canalso be initiated locally or remotely according to a scheduledmaintenance program, which may be during periods of detected systemidleness or during system startup or shutdown, for example.

A technician can remotely access the TSS system via a network or dial-upconnection. By way of example, the TSS system can be accessed via acommunication link established between a remote computing system and thecontroller of the TSS system, assuming the TSS system includes anappropriate communications interface. Alternatively, or in addition, theTSS system can be accessed via a communication link established betweenthe remote computing system and the communications interface of a hostcomputing system which incorporates a TSS system.

Turning now to FIG. 1, there is shown an embodiment of a touch screensensor (TSS) system which employs a touch simulation capability inaccordance with an embodiment of the present invention. The TSS system20 shown in FIG. 1 includes a touch screen sensor 22 which iscommunicatively coupled to a controller 26. In a typical deploymentconfiguration, the TSS 22 is used in combination with a display 24 of ahost computing system 28 to provide for visual and tactile interactionbetween a user and the host computing system 28.

It is understood that the TSS 22 can be implemented as a device separatefrom, but operative with, a display 24 of the host computing system 28.Alternatively, the TSS 22 can be implemented as part of a unitary systemwhich includes a display device, such as a plasma, LCD, or other type ofdisplay technology amenable to incorporation of the TSS 22. It isfurther understood that utility is found in a system defined to includeonly the TSS 22 and controller 26 which, together, can implement a touchsimulation methodology of the present invention.

In the illustrative configuration shown in FIG. 1, communication betweenthe TSS 22 and the host computing system 28 is effected via thecontroller 26. It is noted that one or more TSS controllers 26 can becommunicatively coupled to one or more touch screen sensors 22 and thehost computing system 28. The controller 26 is typically configured toexecute firmware/software that provides for detection of touches appliedto the TSS 22, execution of various calibration and diagnostic routines,and simulation of a touch to the TSS 22 in accordance with theprinciples of the present invention. It is understood that the functionsand routines executed by the controller 26 can alternatively be effectedby a processor or controller of the host computing system 28.

In one particular configuration, for example, the host computing system28 is configured to support an operating system and touch screen driversoftware. The host computing system 28 can further support utilitysoftware and hardware. For example, software can be stored on the hostcomputing system 28 which can be executed to calibrate the touch screensensor 22 and to configure or setup the TSS 22. It will be appreciatedthat the various software/firmware and processing devices used toimplement touch screen sensor processing and functionality in accordancewith the principles of the present invention can be physically orlogically associated with the TSS controller 26, host computing system28, a remote processing system, or distributed amongst two or more ofthe controller 26, host computing system 28, and remote processingsystem.

The controller 26, which may be mounted to a separate card and removablyinstallable within the host computing system chassis, typically includesprocessor and memory devices for storing and executing TSS operatingfirmware and communication firmware for communicating with the hostcomputing system 28. The TSS 22 can be attached to the display 24 andinclude a connector interface for connecting with the controller 26.

In FIG. 2, there is shown a more robust system environment in which atouch screen sensor system and touch simulation methodology of thepresent invention may find utility. In accordance with this embodiment,the host computing system 28 includes a user interface 23 whichincorporates a TSS 22 and a display 24. It is noted that the userinterface 23 shown in FIG. 2 can include other user input or interactiondevices, including a microphone and a speaker, for example. A controller26 is shown coupled to the user interface 23. As previously discussed,the controller 26 may be implemented within the host computing system orthe user interface 23.

The host computing system 28 further includes one or more media drives38 which are configured to access (read and/or write) appropriateportable media 40. For example, the media drives 38 may includes one ormore of a CD-ROM reader/writer, DVD drive, floppy drive, memory cardreader/writer or other type of media drive. The host computing system 28can also include a mass storage device 36, such as a direct accessstorage device (e.g., hard drive) or other form of non-volatile digitalmemory, and system memory 34.

In the configuration shown in FIG. 2, the host computing system 28includes a communication interface 32 which provides an interface forcommunicating with a remote system 46 via a communication link. Thecommunication interface 32 may, for example, be configured to include anetwork interface card (NIC) or other suitable interface forcommunicating with one or more networks 42. For example, thecommunication interface 32 can be connected to a local area networkwhich can provide access to one or more public or private networks forcommunicating with the remote system 46. In this regard, thecommunication interface 32 may communicate with one or more networks 42in conformance with known wired or wireless network protocols,including, for example, an IP (e.g., IPv4 or IPv6), GSM, UMTS/IMT, WAP,GPRS, ATM, SNMP, SONET, TCP/IP, ISDN, FDDI, Ethernet or 100Base-Xprotocol. Communication between the remote system 46 and thecommunication interface 32 of the host computing system 28 can also beestablished via a direct wired or wireless communication link 44, suchas land line, for example.

The remote system 46 can interact with the host computing system 28 in awide variety of manners depending on the desired level of services andfunctionality required for a given application. Such services andfunctionality can include one or more of remote control of the hostcomputing system 28 and/or TSS controller 26, remote touch simulation,remote monitoring, remote diagnostics, remote calibration, and remoteservicing/repair, for example. In most configurations, bi-directionalcommunication is effected between the remote system 46 and thecommunication interface 32. It is understood, however, that in certainsystem configurations, it may only be necessary or desired to providefor uni-directional communication between the remote system 46 and thehost computing system 28.

Referring now to FIG. 3, there is shown a local host computing system28, which incorporates a touch screen sensor 22, which is configured tocommunicate with a remote system 46. In the system configuration shownin FIG. 3, a variety of remote systems 46 are shown for purposes ofillustration. The remote system 46 shown in FIG. 3, for example, can beimplemented as a control console 56 situated remotely from the hostcomputing system 28. A processing system and/or a human operator at thecontrol console 56 can interact with the controller 26 of the TSS 22and/or the host computing system 28 via an appropriate communicationlink. The remote system 46 can also be a node 52 of a network 42.Further, the remote system 46 can be a node 55 of a central system 54.

FIG. 3 further illustrates two possible communication paths by which aremote signal 50 is communicated between the remote system 46 and theTSS controller 26. According to one configuration, the remote signal 50is communicated between the remote system 46 and TSS controller 26 viathe host computing system 28. The remote signal 50 is transmitted and/orreceived by the host computing system 28 via link 50A. The hostcomputing system 28 transmits and/or receives the remote signal 50 or aprocessed form/result of the remote signal 50 to/from the TSS controller26 via link 50C. As such, the TSS controller 26 is indirectly linkedwith the remote system 46 via the host computing system 28 according tothis configuration.

According to another configuration, the remote signal 50 is communicateddirectly between the remote system 46 and TSS controller 26. The remotesignal 50 is transmitted and/or received by the TSS controller 26 vialink 50B. In this configuration, the TSS controller 26 is directlylinked with the remote system 46 via link 50B. The TSS 26 cancommunicate with the host computing system 28 over an appropriateconnection (e.g., link 50C) if such is needed or desired to support TSSservices and functionality. In yet another configuration, the remotesignal 50 can be selectively directed to one or both of the hostcomputing system 28 and TSS controller 26 via links 50A and 50Bdepending on the nature of the remote signal 50 and otherconsiderations.

Turning now to FIG. 4, there is shown a touch screen sensor 70electrically coupled to a controller 75 in accordance with an embodimentof the present invention. According to this embodiment, the TSS 70 isimplemented as a capacitive touch screen sensor. The TSS 70 includes asubstrate 72, such as glass, which has top and rear surfaces 72, 73respectively provided with an electrically conductive coating. The topsurface 72 is the primary surface for sensing touch. The top surface 72is nominally driven with an AC voltage in the range of about 2.5 V toabout 5.0 V. The rear surface 73, which is often referred to as abackshield (e.g., electrical noise shield), is usually driven with thesame voltage as the top surface 72 so that the effective capacitancebetween the top and rear surfaces 72, 73 is reduced to nearly zero.

The TSS 70 is shown to include four corner terminals 74, 76, 78, 80 towhich respective wires 74 a, 76 a, 78 a, 80 a are attached. Each of thewires 74 a, 76 a, 78 a, 80 a is coupled to the TSS controller 75. Thewires 74 a, 76 a, 78 a, 80 a connect their respective corner terminals74, 76, 78, 80 with respective drive/sense circuits 74 b, 76 b, 78 b, 80b provided in the controller 75. An additional wire 73 a connects aterminal (not shown) disposed on the rear surface 73 with a drive/sensecircuit 73 b in the controller 75.

The controller 75 controls the voltage at each of the corner terminals74, 76, 78, 80 and the rear terminal via drive/sense circuits 74 b, 76b, 78 b, 80 b, 73 b to maintain a desired voltage on the top and rearsurfaces 72, 73. During normal operation, the controller 75 maintainsthe top and rear surface voltages at substantially the same voltage. Afinger or stylus touch force applied to the top surface 72 is detectedas an effective small capacitor applied to the top surface 72. Thelocation of the touch on the top surface 72 is determined by currentflow measurements made by the controller 75 via corner drive/sensecircuits 74 b, 76 b, 78 b, 80 b in a manner known in the art.

In accordance with the principles of the present invention, thecontroller 75 can control the drive/sense circuits 74 b, 76 b, 78 b, 80b, and 73 b in a variety of manners in order to simulate a touch on thetouch screen sensor 70. As will be described in greater detail, touchsimulation can be initiated, monitored, and controlled locally and/orremotely.

According to one approach, the controller 75 simulates the effect of atouch to TSS 70 by adjusting the top and rear surface voltages todevelop a potential difference between the top and rear surfaces 72, 73.Developing a potential difference in this manner forces a capacitiveeffect between the top and rear surfaces 72, 73, which is detected bycurrent flow measurements made at the four corner terminals 74, 76, 78,80 by the controller 75.

For example, the top surface 72 can be maintained at a nominal operatingvoltage and the voltage of rear surface 73 can be reduced from thenominal operating voltage, such as to about 0 V for example. Thecapacitive effect resulting from the potential difference developedbetween the top and rear surfaces 72, 73 is detected as an effective orsimulated touch located approximately at the center of the top surface72. When this touch simulation process is repeated over time, changes inthe detected location of the simulated touch can indicate changes in theaccuracy of the touch screen sensing system.

In FIG. 5, there is shown a touch screen sensor configured in accordancewith an embodiment of the present invention. According to thisconfiguration, the TSS 130 includes a linearization electrode pattern132 connected to a top resistive layer 144 which are respectivelyprovided on a top surface 140 of the TSS 130. The linearizationelectrode pattern 132 is configured to have a generally rectangularshape with four corner terminals 134, 135, 136, 137 respectivelyconnected to a TSS controller (not shown) via wires 134 a, 135 a, 136 a,137 a. A rear electrode 142 makes electrical contact with a rearresistive layer 143 respectively provided on a rear surface 141 of theTSS 130.

In normal operation, drive signals are applied to the corner terminals134, 135, 136, 137 via respective drive circuits in the controller, andthe controller measures currents flowing through the corner terminals134, 135, 136, 137 via respective sense circuits in the controller.Touch position is then calculated from the measured currents using knownmethods.

The corner terminals 134, 135, 136, 137 are typically driven with an ACvoltage, and the linearization electrodes 132 distribute the voltageevenly across the top resistive layer 144. The rear electrode 142 andrear resistive layer 143 are typically driven with an AC voltage equalto and in phase with the voltage driving corner terminals 134, 135, 136,137. As such, the rear resistive layer 143 serves as a shield againstnoise and also minimizes parasitic capacitance effects becausenegligible capacitive current flows from top resistive layer 144 to rearresistive layer 143. If the voltage on the rear resistive layer 143 ismade unequal to that on the top resistive layer 144, an equal change incurrent flow at corner terminals 134, 135, 136, 137 will result in anapparent touch to the center of the top surface 140 of TSS 130. Thissimulated touch can be used for diagnostic, calibration, and repairpurposes, such as those described herein.

According to a variation of the touch screen sensor configurationdepicted in FIG. 5, the TSS 130 can include a rear electrode 142 withoutinclusion of a rear resistive layer 143. In this configuration, the rearelectrode 142 can be used as a partial shield below the linearizationelectrode pattern 132, which is a highly sensitive area of the touchscreen sensor 130. Simulating a touch in the absence of a rear resistivelayer 143 is effected by changing the voltage driven onto the rearelectrode 142.

FIG. 6 illustrates another embodiment of a touch screen sensor wellsuited for implementing a touch simulation methodology of the presentinvention. According to this embodiment, the touch screen sensor TSS 250includes a linearization electrode pattern 232 connected to a topresistive layer 244 which are respectively disposed on a top surface 240of the TSS 250. The linearization electrode 232 includes four cornerterminals 234, 235, 236, 237 respectively connected to a TSS controller(not shown) via wires 234 a, 235 a, 236 a, 237 a. The rear electrodearrangement in the embodiment of FIG. 6 includes a number of discreterear electrodes situated on the rear surface 241 of the TSS 250. In theparticular configuration shown in FIG. 6, four rear electrodes 251, 252,253, 254 are located about the perimeter of the rear surface 241, withone of the rear electrodes situated along one of the edge regions of therear surface 241 of the TSS 250. It is understood that the number andlocation of the rear electrodes can vary depending on a particular TSSdesign. As illustrated, rear electrodes 251, 252, 253, 254 makeelectrical contact with a rear resistive layer 243 provided on the rearsurface 241 of the TSS 250.

In a configuration in which multiple rear electrodes are employed, as isthe embodiment shown in FIG. 6, the controller (not shown) drives therear electrodes 251, 252, 253, 254 with an AC voltage equal to thatapplied at corner terminals 234, 235, 236, 237. When controlled in thismanner, the multiple rear electrodes 251, 252, 253, 254 effectivelyperform the same function as the single rear electrode 142 in the TSSembodiment depicted in FIG. 5.

In a diagnostic mode, touch simulation can be effected by varying anumber of drive signal parameters, such as amplitude, phase, andfrequency, relative to one another. According to one approach, and asillustrated in FIG. 13, the controller can apply 270 a first signal to afirst surface of the touch screen sensor. The controller applies 272second signals to the multiple electrodes disposed on or situatedproximate the a second surface of the TSS. The controller simulates 274a touch to the TSS by changing a characteristic of at least one of thesecond signals relative to the first signal.

For example, and with reference to FIG. 6, the rear electrodes 251, 252,253, 254 can be driven with voltages differing in amplitude relative tovoltages applied to other rear electrodes and/or the corner terminals234, 235, 236, 237 on the top surface 240 of the TSS 250. The rearelectrodes 251, 252, 253, 254 can be driven with voltages differing inphase relative to voltages applied to other rear electrodes and/or thecorner terminals 234, 235, 236, 237 on the top surface 240. Further, therear electrodes 251, 252, 253, 254 can be driven with voltages differingin frequency relative to voltages applied to other rear electrodesand/or the corner terminals 234, 235, 236, 237 on the top surface 240.

By way of example, rear electrodes 252 and 254 can be undriven, whilerear electrode 251 is driven with a voltage out of phase with thevoltage applied to corner terminals 234, 235, 236, 237 on the topsurface 240, and rear electrode 253 can be driven with a voltage inphase with the voltage applied to the corner terminals 234, 235, 236,237. In this illustrative example, a simulated touch will be located atpoint 260 shown in FIG. 6. By way of further example, the controller candrive the rear electrodes 251, 252, 253, 254 at DC, or at equalvoltages, of the same frequency, and further drive the corner terminals234, 235, 236, 237 on the top surface 240 at a voltage unequal to thatapplied to the rear electrodes 251, 252, 253, 254. This simulated touch,using this approach, will be located at the center of the top surface240 at point 261.

Independent rear electrodes, such as rear electrodes 251, 252, 253, 254shown in FIG. 6, can be used to simulate a touch with or without thepresence of rear resistive layer 243. If rear resistive layer 243 is notpresent, higher drive voltages must typically be applied to the rearelectrodes in order to simulate a touch.

In accordance with another approach, a non-capacitive technique can beemployed to simulate a touch on a touch screen sensor. In a system suchas that shown in FIGS. 5 and 6, this non-capacitive simulated touchtechnique can be employed in the presence or absence of one or both ofthe rear resistive layer and rear electrode(s). According to thisapproach, and with reference to FIG. 11, a voltage drive signal can beapplied 280 at a number of regions of the touch surface of the TSS. Acurrent flow resulting from application of the voltage drive signals isdetected 282 as the simulated touch.

By way of example, and with particular reference to FIGS. 6 and 12, thecontroller (not shown) can vary 292 the levels of the drive signalsapplied 290 to the corner terminals 234, 235, 236, 237 on the topsurface 240 relative to one another, and measure the resulting currentflows at each of the corner terminals 234, 235, 236, 237. The controllercan then measure the current from each of the corner terminals 234, 235,236, 237 relative to one another. In this way, a simulated touch can begenerated 296.

For example, the controller can increase the drive voltage on all fourcorner terminals 234, 235, 236, 237 on the top surface 240 to simulate atouch to point 61 at the center of TSS 250. The controller can alsoincrease the drive voltage on corner terminals 235 and 236 relative tothe drive signals applied to corner terminals 234 and 237, whilemaintaining a constant touch detect threshold. This will result in asimulated touch at point 260.

Referring now to FIGS. 7 and 8, two embodiments of a touch screen sensorare shown, each of which incorporates an electrically conductivestructure which is either coupled to, or positioned proximate, thesubstrate of the touch screen sensor. In the arrangements shown in FIGS.7 and 8, an electrically conductive structure, which is electricallyisolated from the touch screen sensor substrate, is used in combinationwith the touch screen sensor substrate to effect touch simulation inaccordance with the principles of the present invention. Theelectrically conductive structure can also be effectively used as abackshield to provide for shielding from electrical noise.

In the embodiments shown in FIGS. 7 and 8, a touch screen sensor 300includes a substrate 305 having a top surface 302 provided with aconductive coating. Corner terminals 304, 306, 308, 310 are electricallyconnected to the top conductive surface 302 and a controller (not shown)via wires 304 a, 306 a, 308 a, 310 a. The TSS 300 can include one ormore rear surface electrodes, and may include or exclude a rearresistive layer, as in the configurations shown in FIGS. 5 and 6.Alternatively, or in addition, the electrically conductive structure caninclude one or more electrodes (e.g., 4 electrodes), each of which iscoupled to the controller via a respective wire.

In the embodiment shown in FIG. 7, an electrically conductive structure312 a, such as a thin conductive plate or foil, is situated in a spacedapart relationship with respect to the TSS substrate 305. For example,the conductive structure 312 a may be positioned about ⅛″ from the TSSsubstrate 305. The conductive structure 312 a is electrically coupled tothe controller via a wire 314.

FIG. 8 shows an embodiment in which an electrically conductive structure312 b represents a frame that provides structural support for the TSS300. The frame 312 b may, for example, may be configured for mountingthe TSS 300 within a chassis of a system which incorporates the TSS 300.The frame 312 b is coupled to an edge portion of the TSS substrate 305,with an appropriate coating or material provided to electricallyinsulate the electrically conductive portion of the frame 312 b from theTSS substrate 305. The electrically conductive plate surface 313 of theframe 312 b is situated in a spaced apart relationship with respect tothe TSS substrate 305. The plate surface 313 of the frame 312 b iselectrically coupled to the controller via a wire 314.

According to one touch simulation approach, and as depicted in flowdiagram form in FIG. 9, the controller can apply 350 a first signal tothe top surface 302 of the touch screen sensor 300. The controller canapply 352 a second signal to the electrically conductive structure 312a/b proximate or coupled to the touch screen sensor 300. A touch on thetouch screen sensor is simulated 354 by the controller changing one ofthe first and second signals relative to the other of the first andsecond signals.

As was described previously, the controller can simulate a centered ornon-centered touch on the TSS substrate 305 by varying one or moreparameters of the first and second signals, including one or more of theamplitude, phase, and frequency of the drive signals. For example, andwith reference to FIG. 10, the controller applies drive signals to theTSS substrate 305 and the electrically conductive structure 312 a/b todevelop 360 a potential difference there between. A response to thepotential difference is detected 362 as the simulated touch.

As is shown in the embodiment illustrated in FIG. 14, touch simulationcan be initiated, monitored, and controlled locally, remotely, or bothlocally and remotely. As shown in FIG. 14, a remotely or locallygenerated touch simulation control signal is received 402, 404 by thecontroller of the touch screen sensor. A simulated touch is produced 406in a manner previously discussed. One or more parameters associated withthe simulated touch are detected and stored 408. A non-exhaustive listof such parameters include change in current, impedance, phase, voltage,or frequency; pr a change in the relationship (e.g., ratio) of currents,impedances, phases, voltages, or frequencies. The parameters may bestored locally or at the remote site 410. The parameters associated withtouch simulation are acquired over a period of time. In one approach,the TSS controller or processor of a host computing system analyzes thestored touch simulation parameters and detects a change, if any, in suchparameters. It is noted that this analysis may also be performed at theremote site. A change in a given touch simulation parameter beyond apredetermined limit or range can be indicative of a problem with thetouch screen sensor, such as a change in touch detection accuracy.Analysis and detection of the TSS parameters can be performed locally412, remotely 414, or cooperatively at local and remote sites.

For example, a change detected in a particular TSS parameter can becompared 416 to a predetermined limit or result established from apreviously measured touch simulation limit or result. The comparisonoperation can be performed locally, remotely 418, or cooperatively atlocal and remote sites. Results from a diagnostics procedure performedat the touch screen sensor can be stored and reports generated 420locally and/or at the remote site.

As was discussed previously, touch simulation methodologies of thepresent invention can be implemented in a wide range of touch screensensor technologies. By way of further example, touch simulationmethodologies in accordance with the present invention can beimplemented in a near field imaging (NFI) capacitive touch screensensor. A simplified schematic of an NFI capacitive touch screen sensoris illustrated in FIG. 15.

The NFI capacitive touch screen sensor includes conductive ITO(indium-tin-oxide) bars 515 through 534, deposited on substrate 501,which define the touch sensitive surface. Bar connections 540 through548 connect the ITO bars to an electronic controller (not shown).

A touch is detected by activating bars 515-534 with an AC signal, andmeasuring changes in current flowing in connections 540-548 due tocapacitive coupling from one or more bars to a finger or stylus inproximity to the bar(s). Vertical position is determined by the relativemagnitude of the change in current among the bars. Horizontal positionis determined by measuring the ratio of current change in a bar betweenits left side connection (540-543) and its right side connection(544-548). Additional details of an NFI capacitive touch screen sensorof the type depicted in FIG. 15 are disclosed in U.S. Pat. No.5,650,597, and in commonly owned U.S. Ser. No. 09/998,614, filed Nov.30, 2001, which is hereby incorporated herein. Touch may be simulated inthis system by adding simulation electrodes 505, 506, 507, 508 inproximity to the left and right ends of selected bars or in proximity tothe bar connections as shown. These added electrodes may be placed on orin proximity with the rear surface of substrate 501, or they may beplaced in front of bar ends or connections 540-548. The added electrodesare connected to the electronic controller (not shown). Four simulationelectrodes are shown in FIG. 15 for simplicity, though one simulationelectrode may be placed at the end of each connection 540-548. Duringnormal touch detection, simulation electrodes may be electricallydisconnected, or driven with a signal that is equal in magnitude andphase with the signals driven onto connections 540-548.

A touch may be simulated by driving one of the left side simulationelectrodes 505, 506 and one of the right side simulation electrodes 507,508 with a signal that is unequal to the signals driven onto lines540-548. Simulation electrodes may be grounded, or driven with an ACsignal that is a different magnitude or out of phase with the signals onlines 540-548. For example, grounding electrodes 505 and 507 will resultin a simulated touch in the center of bar 515. Driving electrode 517with an AC signal equal in magnitude and in phase with the signals onlines 540-548, while grounding electrode 505, results in a simulatedtouch near the left end of bar 515. Grounding electrodes 505 and 508simulates a touch to the center of bar 531.

Another touch screen sensor of a technology amenable to automated touchsimulation is a grid capacitive touch screen sensor. FIG. 16 shows agrid capacitive touch screen in accordance with an embodiment of thepresent invention. Electrodes 652-667 are activated sequentially with anAC signal. A finger of stylus in proximity with one or more of theelectrodes 652-667 capacitively couples to them and alters the impedanceof the electrode in proportion to the magnitude of the capacitivecoupling. This impedance change is measured on each electrode, and therelative changes are used to calculate position. Additional details of agrid capacitive touch screen sensor like the type depicted in FIG. 16are disclosed in U.S. Pat. Nos. 4,686,332 and 5,844,506.

Touch simulation on this type of touch screen sensor is similar to thatassociated with NFI capacitive touch screen sensors, in that asimulation electrode 700, 701, 702, 703 near one of the touch electrodes652-667 or near the electrode connections 670-685 may be grounded ordriven with a signal that will couple to touch electrodes and change theelectrode's impedance to simulate a touch. Only four simulationelectrodes are shown in FIG. 16 for simplicity. As few as one simulationelectrode per dimension may be used, or as many as one per touchelectrode.

As an alternative to simulation electrodes constructed on or near thetouch sensor, capacitive coupling to touch electrodes 652-667 orelectrode connections 670-685 may be accomplished by connecting standardcapacitors to electrode connections 670-685. Such capacitors may belocated on the sensor or its cable, or on the electronic controller thatgenerates the signals that drive the sensor.

The foregoing description of the various embodiments of the inventionhas been presented for the purposes of illustration and description. Itis not intended to be exhaustive or to limit the invention to theprecise form disclosed. Many modifications and variations are possiblein light of the above teaching. It is intended that the scope of theinvention be limited not by this detailed description, but rather by theclaims appended hereto.

1. A method of simulating a touch on a touch screen sensor comprising asubstrate having a first surface and a second surface opposing the firstsurface, the method comprising: applying a plurality of voltage drivesignals at a plurality of regions of the touch screen sensor; anddetecting a current flow resulting from application of the plurality ofvoltage drive signals as the simulated touch.
 2. The method of claim 1,wherein the voltage drive signals have substantially equal amplitudes.3. The method of claim 1, wherein at least one of the voltage drivesignals has an amplitude differing from others of the plurality ofvoltage drive signals.
 4. The method of claim 1, wherein detecting thecurrent flow comprises detecting a change in a current flow at each of aplurality of corner regions of the first surface.
 5. The method of claim1, further comprising detecting an impedance change between one cornerregion of the first surface relative to other corner regions of thefirst surface.
 6. The method of claim 1, wherein the voltage drivesignals are applied to first, second, third, and fourth corners of thefirst surface, the first and second corners opposing the third andfourth corners, the method further comprising adjusting each of thevoltage drive signals to a predetermined amplitude, and detecting animpedance responsive to the adjusted voltage drive signals.
 7. Themethod of claim 6, wherein the predetermined amplitude of the voltagedrive signals respectively applied to the first and second corners isdifferent from the predetermined amplitude of the voltage drive signalsrespectively applied to the third and fourth corners.
 8. The method ofclaim 1, wherein the applying and detecting processes are repeated overa duration of time, the method further comprising detecting variationsin the current flow over the duration of time.
 9. The method of claim 1,wherein the applying and detecting processes are repeated over aduration of time, the method further comprising detecting a change in aposition of the simulated touch over the duration of time.
 10. Themethod of claim 9, further comprising generating a message signalassociated with the detected change in simulated touch position, andcommunicating the message signal to a remote location.
 11. The method ofclaim 1, further comprising receiving an initiation signal, andinitiating the applying and detecting processes in response to thereceived initiation signal.
 12. The method of claim 11, wherein theinitiation signal is received from a remote location or a locationproximate the touch screen sensor.
 13. The method of claim 11, whereinthe initiation signal is generated during a predetermined touch screensensor routine.
 14. The method of claim 1, wherein a result of thesimulated touch is compared to one or more predetermined limits, and theresult exceeding the one or more predetermined limits is used to assessoperational fitness of the touch screen sensor.
 15. The method of claim1, wherein a current result of the simulated touch is compared to one ormore previously measured results of the simulated touch, and the currentresult deviating from the previously measured results by a predeterminedamount is used to assess operational fitness of the touch screen sensor.16. The method of claim 1, wherein a result of the simulated touch isused to compensate for inaccuracies of the touch screen sensor or asystem incorporating the touch screen sensor.
 17. A touch sensingsystem, comprising: a touch screen sensor comprising a substrate havinga first surface and a second surface opposing the first surface; and acontroller coupled to the touch screen sensor, the controller configuredto apply a plurality of voltage drive signals at a plurality of regionsof the touch screen sensor, and detect a current flow resulting fromapplication of the plurality of voltage drive signals as the simulatedtouch.
 18. The system of claim 17, wherein the controller maintains thevoltage drive signals at substantially equal amplitudes.
 19. The systemof claim 17, wherein the controller adjusts the amplitude of at leastone of the voltage drive signals to an amplitude differing from anamplitude of others of the plurality of voltage drive signals.
 20. Thesystem of claim 17, wherein the controller detects the current flow bydetecting a change in a current flow at each of a plurality of cornerregions of the first surface.
 21. The system of claim 17, wherein thecontroller detects an impedance change between one corner region of thefirst surface relative to other corner regions of the first surface. 22.The system of claim 17, wherein the controller applies the voltage drivesignals to first, second, third, and fourth corners of the firstsurface, the first and second corners opposing the third and fourthcorners, the controller adjusting each of the voltage drive signals to apredetermined amplitude, and detecting an impedance responsive to theadjusted voltage drive signals.
 23. The system of claim 22, wherein thepredetermined amplitude of the voltage drive signals respectivelyapplied to the first and second corners is different from thepredetermined amplitude of the voltage drive signals respectivelyapplied to the third and fourth corners.
 24. The system of claim 17,wherein the controller repeats the applying and detecting processes overa duration of time, the controller detecting variations in the currentflow over the duration of time.
 25. The system of claim 17, wherein thecontroller repeats the applying and detecting processes over a durationof time, the controller detecting a change in a position of thesimulated touch over the duration of time.
 26. The system of claim 25,wherein the controller or a host processing system coupled to thecontroller generates a message signal associated with the detectedchange in simulated touch position, the message signal communicated to aremote location.
 27. The system of claim 17, wherein the controllerreceives an initiation signal from a remote source or a host processingsystem coupled to the controller, and controller initiating the applyingand detecting processes in response to the received initiation signal.28. The system of claim 27, wherein the initiation signal is generatedduring a predetermined touch screen sensor routine or during a period ofdetected system idleness.
 29. The system of claim 17, wherein a resultof the simulated touch is compared to one or more predetermined limits,and the result exceeding the one or more predetermined limits is used toassess operational fitness of the touch screen sensor.
 30. The system ofclaim 17, wherein a current result of the simulated touch is compared toone or more previously measured results of the simulated touch, and thecurrent result deviating from the previously measured results by apredetermined amount is used to assess operational fitness of the touchscreen sensor.
 31. The system of claim 17, wherein a result of thesimulated touch is used to compensate for inaccuracies of the touchscreen sensor or a system incorporating the touch screen sensor.